The present invention relates to a new and improved process for manufacturing pure diosmin (5,7,3'-trihydroxy-4'-methoxyflavone-7-rhamnoglucoside, molecular formula: C.sub.28 H.sub.32 O.sub.15) suitable as a therapeutic agent. The process is a semi-synthetic process which starts from hesperidin obtained as a natural product.
Diosmin is a natural bioflavonoid which, for instance, can be found in citrus fruits. Its use as a tonic agent for veins or as a liver protective agent is well known.
Publications heretofore described a number of techniques for obtaining diosmin from hesperidin. The authors of such works manufactured the diosmin in small quantities in order to obtain proof of the structure of the naturally obtained diosmin. The diosmin manufactured in accordance with the process described in the prior art publications is generally only obtained with small yield and purity. A method for manufacturing diosmin on an industrial scale for using the flavonoid as a therapeutic agent has not heretofore been described.